Quick answer: a full freezer keeps food frozen for around 48 hours and a half-full one for around 24 hours — as long as you keep the door shut. A fridge keeps food cold for only about 4 hours.
Keep the doors closed
Every time you open the door, cold air escapes. Resist checking. If you know a long cut is coming (for example a planned outage or a storm warning), turn the freezer to its coldest setting a few hours before.
Make your freezer last longer
- Fill the gaps. A full freezer stays cold longer. Fill empty space with bottles of water (leave room for expansion) — they also become emergency drinking water.
- Group food together so items keep each other cold.
- Cover the freezer with a blanket or duvet for extra insulation, but don't block any vents once power returns.
- Move fridge essentials like medicines or baby milk into a cool box with ice packs early.
After the power comes back
- Food that still has ice crystals or feels as cold as when it was in a working fridge can usually be refrozen.
- Throw away raw meat, fish, ready meals and dairy that have fully thawed and warmed up.
- Fridge food like milk, meat, cooked leftovers and soft cheese should be thrown away if it has been warm for several hours.
- If in doubt, throw it out. You can't tell if food is safe by smelling it.
Check your insurance
Some home contents policies cover freezer food lost in a power cut. Take photos before throwing anything away.
For light, warmth and charging during a cut, see our power cut kit and what to do in a power cut.
Frequently asked questions
How long does a fridge stay cold without power?
About 4 hours if the door stays closed. After that, perishable food like milk, meat and leftovers may not be safe.
Can I refreeze food that has partly defrosted?
Food that still has ice crystals or is still fridge-cold can usually be refrozen. Food that has fully thawed and warmed up should be cooked straight away or thrown out.
Does home insurance cover food lost in a power cut?
Some contents policies do, often with a limit. Check your policy and take photos before throwing food away.